diff --git a/src/ol/layer/vectorlayer.js b/src/ol/layer/vectorlayer.js
index a50719c9ab..d777199f5e 100644
--- a/src/ol/layer/vectorlayer.js
+++ b/src/ol/layer/vectorlayer.js
@@ -326,12 +326,12 @@ ol.layer.Vector.prototype.parseFeatures = function(data, parser, projection) {
   var callback = function(feature, type) {
     return lookup[type];
   };
-  if (typeof data === 'string') {
-    goog.asserts.assert(typeof parser.readFeaturesFromString === 'function',
+  if (goog.isString(data)) {
+    goog.asserts.assert(goog.isFunction(parser.readFeaturesFromString),
         'Expected a parser with readFeaturesFromString method.');
     features = parser.readFeaturesFromString(data, {callback: callback});
-  } else if (typeof data === 'object') {
-    goog.asserts.assert(typeof parser.readFeaturesFromObject === 'function',
+  } else if (goog.isObject(data)) {
+    goog.asserts.assert(goog.isFunction(parser.readFeaturesFromObject),
         'Expected a parser with a readFeaturesFromObject method.');
     features = parser.readFeaturesFromObject(data, {callback: callback});
   } else {
diff --git a/src/ol/parser/ogc/exceptionreport.js b/src/ol/parser/ogc/exceptionreport.js
index ce2e4990c1..606e96f26a 100644
--- a/src/ol/parser/ogc/exceptionreport.js
+++ b/src/ol/parser/ogc/exceptionreport.js
@@ -84,7 +84,7 @@ goog.inherits(ol.parser.ogc.ExceptionReport, ol.parser.XML);
  * @return {Object} Information about the exceptions that occurred.
  */
 ol.parser.ogc.ExceptionReport.prototype.read = function(data) {
-  if (typeof data == 'string') {
+  if (goog.isString(data)) {
     data = goog.dom.xml.loadXml(data);
   }
   var exceptionInfo = {};
diff --git a/src/ol/parser/ogc/versioned.js b/src/ol/parser/ogc/versioned.js
index 99970abe9d..2685b66e93 100644
--- a/src/ol/parser/ogc/versioned.js
+++ b/src/ol/parser/ogc/versioned.js
@@ -14,12 +14,12 @@ ol.parser.ogc.Versioned = function(opt_options) {
   this.defaultVersion = options.defaultVersion || null;
   this.version = options.version;
   this.profile = options.profile;
-  if (options.allowFallback !== undefined) {
+  if (goog.isDef(options.allowFallback)) {
     this.allowFallback = options.allowFallback;
   } else {
     this.allowFallback = false;
   }
-  if (options.stringifyOutput !== undefined) {
+  if (goog.isDef(options.stringifyOutput)) {
     this.stringifyOutput = options.stringifyOutput;
   } else {
     this.stringifyOutput = false;
@@ -103,7 +103,7 @@ ol.parser.ogc.Versioned.prototype.write = function(obj, opt_options) {
  * @return {Object} An object representing the document.
  */
 ol.parser.ogc.Versioned.prototype.read = function(data, opt_options) {
-  if (typeof data == 'string') {
+  if (goog.isString(data)) {
     data = goog.dom.xml.loadXml(data);
   }
   var root = data.documentElement;
diff --git a/src/ol/parser/ogc/wmscapabilities_v1.js b/src/ol/parser/ogc/wmscapabilities_v1.js
index 860392da99..018fdf2ab5 100644
--- a/src/ol/parser/ogc/wmscapabilities_v1.js
+++ b/src/ol/parser/ogc/wmscapabilities_v1.js
@@ -230,10 +230,10 @@ ol.parser.ogc.WMSCapabilities_v1 = function() {
             layer['prefix'] = parts[0];
           }
           capability['layers'].push(layer);
-          if (layer['formats'] === undefined) {
+          if (!goog.isDef(layer['formats'])) {
             layer['formats'] = request['getmap']['formats'];
           }
-          if (layer['infoFormats'] === undefined && gfi) {
+          if (!goog.isDef(layer['infoFormats']) && gfi) {
             layer['infoFormats'] = gfi['formats'];
           }
         }
@@ -303,7 +303,7 @@ goog.inherits(ol.parser.ogc.WMSCapabilities_v1, ol.parser.XML);
  * @return {Object} An object representing the document.
  */
 ol.parser.ogc.WMSCapabilities_v1.prototype.read = function(data) {
-  if (typeof data == 'string') {
+  if (goog.isString(data)) {
     data = goog.dom.xml.loadXml(data);
   }
   if (data && data.nodeType == 9) {
diff --git a/src/ol/parser/ogc/wmtscapabilities_v1_0_0.js b/src/ol/parser/ogc/wmtscapabilities_v1_0_0.js
index fa35ec4c5e..1a6b636d1b 100644
--- a/src/ol/parser/ogc/wmtscapabilities_v1_0_0.js
+++ b/src/ol/parser/ogc/wmtscapabilities_v1_0_0.js
@@ -154,7 +154,7 @@ goog.inherits(ol.parser.ogc.WMTSCapabilities_v1_0_0, ol.parser.XML);
  * @return {Object} An object representing the document.
  */
 ol.parser.ogc.WMTSCapabilities_v1_0_0.prototype.read = function(data) {
-  if (typeof data == 'string') {
+  if (goog.isString(data)) {
     data = goog.dom.xml.loadXml(data);
   }
   if (data && data.nodeType == 9) {